Energy and Exergy Analysis of the Danish Industry Sector

A detailed analysis of the Danish industry is presented in this paper using the energy, exergy and embodied exergy methods. The 22 most energy-intensive process industries, which represent about 80% of the total primary energy use of the industry, were modelled and analysed in details for the years 2006 and 2012. The energy and exergy losses, as well as the exergy destruction, were established, together with the embodied ones, by including the transformation processes in the utility sector. The energy and exergy efficiencies for each sub-sector were calculated in a final step and ranged from 12% to 56% in 2012. Industries with high-temperature processes, such as the cement and metal production sectors, present the highest exergy efficiencies but the lowest energy ones. The opposite conclusion is drawn for the food, paper and chemical industries. The exergy losses, which indicate the potential for recovering and valorising heat, amounted to 3,800 TJ for the same year. Meanwhile, the embodied exergy losses, from the central production of heat and power, exceeded 8,700 TJ. The comparison of the embodied energy efficiencies from 2006 to 2012 shows a clear increase of 4.2%-points, but this trend is not seen with the embodied exergy efficiency, which remains at around 29% for the Danish industry. This analysis shows that there are still large potentials to recover waste heat in most Danish industrial sectors and thus to increase their efficiencies.